1. Field of the Invention
The present invention relates generally to electrode structures for use in batteries. More particularly, this invention relates to protected anode architectures that provide a sealed enclosure for a protected active metal anode (e.g., Li) in order to facilitate its incorporation/optimization into a variety of battery cell structures.
2. Description of Related Art
The low equivalent weight of alkali metals, such as lithium, renders them particularly attractive as a battery electrode component. However, alkali metal anodes based on Li (e.g., Li metal foil, LiSn, LiC6) are highly reactive in ambient atmosphere, and are known to corrode or degrade in a variety of electrolytes, such as aqueous and even non-aqueous systems. Accordingly, the incorporation of lithium based anodes into electrochemical devices requires special processing, and the selection of suitable electrolytes is limited, as is the choice of cathode system.
Typically, lithium battery manufacture is conducted in inert environments in order to guard against degradation of lithium until it is hermetically sealed within a battery cell container. Moreover, in conventional active metal batteries such as lithium batteries, the lithium electrode (anode), microporous separator (e.g., Celgard), and positive electrode (cathode) are all in intimate contact with the organic aprotic solvent in the liquid electrolyte. So, the choice of battery cell chemistry is limited to systems in which the electrolyte is stable to both the cathode and the anode. Moreover, conventional cell architectures do not permit optimization of electrolytes or cathode-side solvent systems without impacting anode stability or performance and vice-versa
Prior work in the present applicants' laboratories has led to the development of technology for protecting active metal anodes with highly ionically conductive protective membrane architectures. These protected active metal anode structures and associated electrochemical cells, are described in applicants' published US Applications US 2004/0197641, now U.S. Pat. No. 7,645,543, issued Jan. 12, 2010), US 2005/0175894, now U.S. Pat. No. 7,282,295, issued Oct. 16, 2007), and their corresponding International Patent Applications WO 2005/038953 and WO 2005/083829, respectively. These developments represent major advances in active metal battery technology, for instance rendering possible functional Li/air and Li/water batteries.
This technology would be further advanced by the development of appropriate barrier seals that would facilitate and/or optimize the incorporation of these protected active metal anodes into a variety of cell structures.